That's not necessarily blind firing, that's just being an asshole. Kids that use transparent "tactical shields" in CQB aren't blind firing, they're just being assholes. If there is a man-made hole big enough for you to aim down your sights, then I think its okay. A few holes in a pallet would be fine, some random hole in a wall is not.
I was once accused of blind fire because I shot at a guy that was behind brush, and I could see his outline.
Guardians of Asgaard - KF32
VFC H&K 416C
VFC KAC SR16 JL Billet SBR
TM FN Five-seveN